Crabs more than three feet across have invaded the Antarctic abyss, wiped out the local wildlife and now threaten to ruin ecosystems that have evolved over 14 million years.

Three years ago, researchers predicted that as the deep waters of the Southern Ocean warmed, king crabs would invade Antarctica within 100 years.

But video taken by a remotely operated submersible shows that more than a million specimens of Neolithodes yaldwyni have already colonized Palmer Deep, a basin that forms a hollow in the Antarctic Peninsula’s continental shelf. They have been found in the deepest parts, from about 3,000 to 4,500 feet below sea level.

Images taken by the submersible show how the crabs prod, probe, gash and puncture delicate sediments with the tips of their long legs. “This is likely to alter sediment processes, such as the rate at which organic matter is buried, which will affect the diversity of animal communities living in the sediments,” says Craig Smith of the University of Hawaii at Manoa, whose team discovered the scarlet invaders.

The crabs appear to have a voracious appetite. Echinoderms — sea urchins, sea lilies, sea cucumbers, starfish and brittle stars — have vanished from occupied areas, and the number of species in colonized areas is just a quarter of that in areas that have escaped the invasion.

The crabs come from farther north, moving in as Antarctic waters have warmed. In 1982, the minimum temperature there was 34.2 degrees, too cold for king crabs. But by last year it had risen to a balmier 34.6 degrees.